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Tuesday, December 10, 2013

The SLS and the Case for a Reusable Lunar Lander

NASA OTV with single stage reusable lunar lander (credit NASA)

by Marcel Williams

In 2009, President Obama inherited an annual manned spaceflight related budget from the previous administration of approximately $8.4 billion. Approximately $3 billion was for operating the Space Shuttle. Another $2 billion was for the ISS program. And an additional $3.4 billion was for the future Constellation program with primary funding going towards the development of the Orion manned spacecraft and the Ares I launch vehicle. Further increases in Orion and Ares I funding were set to occur after the end of the Shuttle program. But significant funding for the core vehicle of the Ares V heavy lift vehicle, its upper stage, and for the Altair lunar lander weren't set to occur until after Orion and Ares I development was completed and the ISS program had come to an end.

A year later, of course, the Obama administration canceled the Constellation program and, surprisingly, NASA's efforts to return to the Moon. Instead, the Obama administration decided to extend the life of the ISS program at least until 2020 while also deciding to fund the private development of private commercial manned space vehicles for accessing LEO and the ISS. Long term beyond LEO goals were set by the administration for a manned spaceflight to a NEO asteroid in the mid 2020s and an orbital mission to Mars in the 2030s. But no vehicles were to be immediately financed and developed for such ventures. President Obama's decision still left NASA with a few billion dollars of unused manned spaceflight related funds which the President decided to utilize in research on future heavy lift vehicles and for solving the problems of manned beyond LEO space travel.

Democrat and Republican advocates of NASA's manned space program, however, were stunned by the President's decision to terminate the Constellation program and to cancel NASA's efforts to return to the Moon. And they defiantly passed legislation for the immediate funding of a heavy lift vehicle (SLS) and for the continued development of the Orion spacecraft (MPCV).

Space Launch System crew vehicle and cargo vehicle

The Orion (MPCV) program is now scheduled for an unmanned test of its Command Module in 2014 aboard a Delta IV heavy. And the unmanned test of the SLS heavy lift vehicle plus the MPCV with its European developed Service Module is scheduled to occur before the end of 2017.

But how and when the SLS and MPCV will be used for manned beyond LEO missions is far more ambiguous. While some in Congress still argue for manned lunar missions and even a lunar base, the White House continues to argue for an-- anything but the Moon policy.

While the current administration is trying to keep Americans from returning to the Moon, other nations are focusing on the lunar surface's vast resources and even its strategic position around the Earth. China, of course, has recently launched its first robotic attempt to explore the surface of the Moon and has repeatedly stated its long term intentions of sending people to the Moon and to establish a permanent Chinese presence on the lunar surface for the exploitation of lunar resources. Russia and a few other nations also appear to be focusing on sending humans to the surface of the Moon.

The Obama administration has countered criticism of its anti-lunar stance by arguing that manned lunar missions would inhibit NASA's ability to eventually send humans to Mars. However, many NASA scientist have argued that a fuel producing lunar outpost could be an essential key to eventually getting humans to the surface of Mars. China appears to have a similar perspective.

But can NASA realistically establish a permanent human presence on the surface of the Moon and, eventually, on Mars under the political constraints of its current manned spaceflight budget? Was the $8.4 billion a year manned spaceflight related budget that President Obama originally inherited from the previous administration enough to get the job done over then next 25 years?

The SLS/MPCV program is currently being funded at about $3 billion a year. However, the Service Module of the MPCV is now being funded and developed by the European space agency. An additional $300 million dollars is being used for SLS ground systems development. So what is currently being spent by NASA on the SLS/MPCV program is close to what was being spent on the Constellation program when President Obama came into office. But now, of course, there's no longer the financial burden of a $3 billion a year Space Shuttle program.

The Center for Strategic and International Studies (CSIS) has estimated that the cost of developing the two stage Altair lunar lander at approximately $12 billion. But NASA director Charlie Bolden estimates the cost of developing a lunar landing vehicle at approximately $8 to $10 billion. It took six years for NASA and its private vendors to develop the lunar module that took Neil Armstrong and Buzz Aldrin to the lunar surface in 1969. If we assume a 7 year development time for the next manned landing vehicle then the annual cost of funding such a vehicle should range between $1.1 billion to 1.7 billion a year. That would raise the manned spaceflight related budget from a range of $4.4 billion to up to $5 billion annually.

However, the CSIS had estimated the development cost of a lunar outpost at approximately $17 billion. Over a ten year period of development and deployment, that would mean an additional $1.7 billion in annual funding. That would raise the NASA manned spaceflight related budget to perhaps $6.1 yo $6.7 billion a year. However, once the lunar outpost is established, the CSIS estimated that the annual recurring cost would be $7.35 billion annual-- if lunar resources are not utilized. Of course, one of the principal reasons for returning to the Moon is to utilize and even export lunar resources for water, air, and rocket fuel in order to reduce the cost of space travel.

So with an $8.4 billion a year manned spaceflight budget, it appears that NASA would have plenty of funds to return to the Moon even if they used the rather expensive Constellation architecture.

But NASA is still running a very expensive LEO program in the form of the ISS and Commercial Crew development. Combined, these two programs cost nearly $3.4 billion a year. At less than $400 million a year, the Commercial Crew program is probably being seriously underfunded. But some in Congress are still talking about extending the life of the $3 billion a year ISS program beyond 2020-- all the way to 2028.

So its not a question as to whether NASA can afford a beyond LEO program. $8.4 billion appears to be more than enough funding. But its pretty obvious that NASA can't afford a big beyond LEO program plus a big LEO program-- unless it receives a nearly $2 billion increase in its annual manned spaceflight related budget? And Congress, of course, is in no mood to increase the NASA budget during a time of huge budget deficits-- especially as long as the direction of NASA's beyond LEO program remains in ambiguity.

President Obama only has a few more years left in office, however. And by the time the first SLS heavy lift vehicle is being tested for its first flight in 2017, a new president will be in office. So the next president will inherit a manned space program with a new heavy lift vehicle cable of placing more than 70 to 105 tonnes into low Earth orbit when it is fully operational and will also be capable of placing at least 30 tonnes practically anywhere within cis-lunar space. But future astronauts will still be restricted to orbital space unless an extraterrestrial landing vehicle is developed.

The United States currently has a President at the lowest point in his national popularity who also appears to have very little interest in manned space travel. So the time may be right for Congress to take the lead again with bipartisan Democratic and Republican support in order to start seriously fund an extraterrestrial landing vehicle (ETLV) for the SLS by 2015.

Funding could come from either an increase in the NASA budget in 2015 or a decrease in funding for other NASA projects. For instance, since a test launch of the MPCV Command Module will be launched into orbit in 2014 and NASA is no longer required to fund the development of the MPCV Service Module which is being developed by the Europeans, perhaps substantial cuts in the Command Module development could occur after 2014. The ISS program is also an internationally funded program. If NASA cut ISS funding back to 2009 levels ($2 billion a year) in 2015, a billion dollars could be placed into funding lunar lander development.

NASA reusable lunar lander concept on the Moon (Credit NASA)

Lockheed-Martin recently concluded that lunar lander development cost and recurring cost could be substantially reduced if a reusable single staged vehicle were developed instead of a two staged vehicle due to reduced vehicle mass, reductions in vehicle components, and reduced vehicle complexity. NASA reached a similar conclusion back in the late 1980s when JPL proposed its own single stage LOX/LH2 lunar landing vehicle.

Such an ETLV should be a reusable single staged vehicle capable of landing not only on the lunar surface but also on the surface of the Martian moons: Phobos and Deimos and maybe even on the surface of Mars if a ballute or hyper cone are added along with a heat shield. Such a vehicle should also be capable of utilizing extraterrestrial fuel resources on the Moon, the moons of Mars, and on the surface of Mars.

Here, I introducea lunar vehicle concept that I've toyed around with for the last couple of years that's specifically designed to take advantage of the large 8.4 to 10 meter SLS cargo fairing. I call this notional crew vehicle, the ETLV-2. And I will elaborate upon the specifics of this vehicle concept, and its cargo, orbital transfer, and fuel depot vehicle variants, in future post.

But basically, the crew version of the ETLV-2 concept utilizes just two common bulkhead cryotanks each capable of storing up to 14 tonnes of LOX/LH2 fuel. The crew cabin and the twin airlocks are both derived from fuel tank technology, having the same diameter as the fuel tanks in order to further reduce vehicle development cost and recurring cost. So a standard cryotank diameter somewhere between 2.5 to 3 meters would have to be firmly established before the vehicle went into development and eventual production.

Four RL-10 derived CECE (Common Extensible Cryogenic Engine) engines would enhance vehicle safety with engine out capability and would be capable of up to 50 restarts. This should enable the vehicle to be used for at least 10 round trips from the Earth-Moon Lagrange points to the lunar surface which should further reduce recurring cost. Recurring cost could be reduced even further if the engines could eventually be replaced as suggest by Spudis and Lavoie in their lunar architecture concept. A throttle capability ranging from 104% of thrust down to just 5.6%, should allow the CECE engines to enable the ETLV-2 to take off and land on celestial worlds as large as Mars or as small as the moons of Mars.

Utilizing Integrated Vehicle Fluid (IVF) technology currently being developed by the ULA, some ullage gases could be used for attitude control. And with NASA emerging cryocooler technology, ullage gases could be re-liquified, eliminating any significant boil-off of hydrogen and oxygen. The cryotank derived crew habitat would have three floor levels and would be capable of accommodating at least six to eight crew members plus the life support systems. The twin cryotank derived airlocks allows more room within the cabin while allowing astronauts to leave the vehicle without having to decompress and then re-pressurize the crew cabin.

When fully manned and fueled, the ETLV-2 should weigh less than 37 tonnes and be capable of departing from EML1 to land on the Moon and then return EML1 on a single fueling, and vice versa, once the ETLV-2 can be refueled with cryogenic hydrogen and oxygen manufactured on the lunar surface. The addition of an ETLV-2 derived reusable OTV (Orbital Transfer Vehicles) with an aerobraker that could travel between LEO and L1, could also give private Commercial Crew vehicle passengers flown to LEO easy access-- all the way to the surface of the Moon. I will discuss this architectural possibility in a future post.

"The knowledge that we have now is but a fraction of the knowledge we must get, whether for peaceful use or for national defense. We must depend on intensive research to acquire the further knowledge we need ... These are truths that every scientist knows. They are truths that the American people need to understand." (Harry S. Truman 1948).